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Commit 2b1b712f authored by H. Peter Anvin's avatar H. Peter Anvin
Browse files

x86, reboot: Drop redundant write of reboot_mode 

We write reboot_mode to BIOS location 0x472 in
native_machine_emergency_restart() (reboot.c:542) already, there is no
need to then write it again in machine_real_restart().

This means nothing gets written there for MRR_APM, but the APM call is
a poweroff call and doesn't use this memory location.

Link: http://lkml.kernel.org/n/tip-3i0pfh44c1e3jv5lab0cf7sc@git.kernel.org


Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
parent 65051397

arch/x86/kernel/reboot.c

+0 −8
Original line number Diff line number Diff line
@@ -179,14 +179,6 @@ void __noreturn machine_real_restart(unsigned int type) 
	write_cr3(real_mode_header->trampoline_pgd);

#endif



	/*

	 * Write 0x1234 to absolute memory location 0x472.  The BIOS reads

	 * this on booting to tell it to "Bypass memory test (also warm

	 * boot)".  This seems like a fairly standard thing that gets set by

	 * REBOOT.COM programs, and the previous reset routine did this

	 * too. */

	*((unsigned short *)0x472) = reboot_mode;



	/* Jump to the identity-mapped low memory code */

#ifdef CONFIG_X86_32

	asm volatile("jmpl *%0" : :